Gear-Up: Engine shutdown?

[PostmasterGeneral]

A few other threads had me thinking, and I wanted to start a discussion. Single engine, multi engine, let’s discuss pistons specifically since a running free-turbine can “technically” be okay if you smack a prop.

Let’s say you’re into a forced landing situation, gear up. You’re going to smack a prop, no matter what. Do you keep the engine running, because it needs to be torn down regardless, and might need a go-around? Or do you shut it down and glide in to minimize damage? There are pros and cons to each, I don’t think there is really a right or wrong answer. But it sparks an interesting discussion.

[PT6A]

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[C-GGGQ]

I'll second the above post. Once final and gliding to the runway. Idle cut off, feather, shut off fuel. Might not "save" the engine but I'd hazard that the props will now bend/ break clean(ish) vs explode sending shards god knows where (especially in a light twin with them basically beside you)

[C.W.E.]

Same here, unless there were some extenuating circumstances I would plan on shutting down the engine's to minimise cost of repair.

[PostmasterGeneral]

Same here, unless there were some extenuating circumstances I would plan on shutting down the engine's to minimise cost of repair.

Not disagreeing whatsoever, but in another thread there was the mentality that the engines needed to be rebuilt no matter what, and the deductible is the same, so why take away the option of a go-around?

[PT6A]

In the aircraft I fly, I don’t think shutting the engines down would make the outcome for the props / engines much better. The power sections and props are toast regardless. I’m more interested in preventing metal from coming into the fuselage and reducing the risk of a fire should something go south.

[Schooner69A]

It would be interesting to ascertain how many cabins were compromised by prop pieces during the many inadvertent gear up landings there have been. That should give some basis for decisions...

[digits_]

What does the POH say? Or the QRH/checklist?

The biggest advantage would be if you could combine it with feathered 2 blade props that are put horizontal with the starter. Which is something I would only intentionally do in a very light twin.
If you can't do that, then feathering could potentially put more torque/force on the engine.

The most general procedure I would do, would probably be to wait till touchdown of a main gear (or at flare altitude if the gear is fully up) and shutdown the engines at that point. Minimal risk of fire, no big power driving the props, and control as long as possible.

[fish4life]

It would be interesting to ascertain how many cabins were compromised by prop pieces during the many inadvertent gear up landings there have been. That should give some basis for decisions...

Google “jazz Q400 gear collapse” and it tells me all I need to know, I’m shutting it down.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 4w0177.asp

[Heliian]

Leave them running until landing is assured, I thought that was common.

A free turbine will still need a rebuild and will cost more than any piston rebuild.

It would be interesting to ascertain how many cabins were compromised by prop pieces during the many inadvertent gear up landings there have been. That should give some basis for decisions...

Google “jazz Q400 gear collapse” and it tells me all I need to know, I’m shutting it down.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 4w0177.asp

Minor injuries

[PositiveRate27]

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[PT6A]

The metro that went off the runway in Thompson a few months ago had one propeller blade sticking through the cabin door. This wasn’t a gear up issue but with more aircraft having composite blades, I’d rather not having one spinning with power as it makes contact with the ground.

[Zaibatsu]

Looking at most gear up landings and seeing a few of them myself (never done one), it’s far less catastrophic than people who’ve seen too many Hollywood portrayals of it.

The difference in energy between a windmilling prop and one at idle is minimal. Most piston aircraft have aluminum propellers. The only light piston retractable aircraft I know of that could shed a blade into the cockpit/cabin is the Aerostar. Most are well forward. A feathered prop that’s going to hit the ground dead on is going to tweak or break the crank flange. To clock it is going to take time meaning the engines have to be shut down much prior, increasing the risk of undershooting if you can’t add power or overshooting if you padded your airspeed too much on what is now a very clean aircraft.

For sure, as soon as you hit, turn everything off. History shows us it’s electrical that will be the most likely source of post crash fire and the most important thing to turn off since we can’t turn off fuel at the source.

[200hr Wonder]

Don't forget that when you shut them down, and pull fire handles, select fuel off etc. you are closing some fuel and hydraulic valves so that should you go off the runway you are doing your best to keep flammables contained. Another reason I would do it.

[fish4life]

Leave them running until landing is assured, I thought that was common.

A free turbine will still need a rebuild and will cost more than any piston rebuild.

It would be interesting to ascertain how many cabins were compromised by prop pieces during the many inadvertent gear up landings there have been. That should give some basis for decisions...

Google “jazz Q400 gear collapse” and it tells me all I need to know, I’m shutting it down.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 4w0177.asp

Minor injuries

Only minor by pure luck, if the person was leaned forward or back it could have killed them

[Maynard]

Same here, unless there were some extenuating circumstances I would plan on shutting down the engine's to minimise cost of repair.

Not disagreeing whatsoever, but in another thread there was the mentality that the engines needed to be rebuilt no matter what, and the deductible is the same, so why take away the option of a go-around?

A light twin is slow enough you could wait until your over the numbers and shut it down. There’s practically 0 reason you’d need to go around at that point, since everyone knows your coming in with no gear. If the props both stop so the props don’t strike, there’s no reason for a rebuild? Inspection, sure. The idea of keeping engines running incase of a go around sounds like something instructors made up at some point.....

[Adam Oke]

Our QRH for the Q400 suggests a shutdown.

The QRH doesn't lead you to that decision. The Gear Indicator Malfunction checklist is pretty short and sweet and is hoping for a good outcome. If you still have one of the landing gear up, or all of them up as the original scenario suggests -- Bombardier issued a Flight Operations Service Letter 17 June 2014 that indicates engines running for an all gear up scenario.

"It is possible to safely land the Dash 8 with all gear retracted. The geometry of the aircraft is such that the propellers should not come in contact with the runway in an all gear up landing if the wings are maintained level throughout the landing."

later stating....

"Unless there is propeller/ground contact during the landing, requiring an immediate engine shut down, feather and secure once the aircraft has some to a stop"

There is a note that prefaces all of this: "Note: The final decision with respect to the use of procedures outside those given in the AFM will remain with the PIC"

Food for thought.

[PositiveRate27]

I see I’m mistaken. Thank you for that correction.

[cncpc]

I've had lights out and did the drill. I always pull the mixtures back and feather on CS props. At the threshold, right height, right speed.

I don't see the logic of why you would need a rebuild on a gear not down incident, unless you kept the engine(s) operating.

If your engine is shut down, and it has any kind of compression, the prop will stop in the flare, if not before.

[digits_]

I've had lights out and did the drill. I always pull the mixtures back and feather on CS props. At the threshold, right height, right speed.

I don't see the logic of why you would need a rebuild on a gear not down incident, unless you kept the engine(s) operating.

If your engine is shut down, and it has any kind of compression, the prop will stop in the flare, if not before.

If you are concerned about the engine, why would you feather the props?